Data collection as part of the Deepwater Horizion Carcass Drift Study (Bird Study #1D) occurred during July and August, 2011. Data were collected by R.G. Ford Consulting Company (RGFCC) and Biodiversity Research Institute (BRI), under contract to the U.S. Fish and Wildlife Service, and CardnoENTRIX personnel, under contract to the Responsible Party. There were two main objectives: to quantify the length of time study carcasses float prior to sinking, and quantify the proportion of study carcasses that do not sink and eventually become beached or stranded within the area searched for bird carcasses during the Deepwater Horizon Oil Spill. This information was used in the Trustees' quantification of avian mortality caused by the oil spill. Bird carcasses and dummies were dropped from boats and helicopters during July, 2011. Data collected on the deployment of each carcass and dummy are found in this Drift Deployments dataset. This data was recorded on field datasheets for some of the helicopter and boat drops, and also directly into an onboard computer (electronic datasheets) during helicopter drops on certain dates. After deployment, drifters were tracked by aerial, boat, and ground teams. Data collected on sightings of the drifters are captured in the Drifter Sightings dataset. Additional details on Bird Study #1D field efforts and results are provided in the work plan and End of Study Report (Draft Final End of Study Report Using Radio Telemetry to Determine the Fates of Bird Carcasses Drifting in the Northern Gulf of Mexico (Carcass Drift Study - Bird Study #1D), RGFCC 2/24/2014).